Patients with non-ischemic dilated cardiomyopathy (DCM)
often die suddenly due to malignant ventricular arrhythmias. The objective of
the study was to analyze clinical characteristics and outcome of patients with
DCM who received an implantable defibrillator (ICD) in terms of arrhythmia recurrence,
compared with a control group of patients with a healed
myocardial infarction (MI). The study group comprised 33 patients with DCM and
88 patients with MI. All ICD´s allowed electrogram storage.

Results: There were no
significant differences among the clinical characteristics; age (63±9
vs. 63±10 years), sex (male, 95% vs. 97%) and prescription of antiarrhythmic
drugs (60% vs. 55%). DCM patients had a lower ejection fraction, (28±9
vs. 33±10, p=0.03) and a higher functional class (III/IV 36% vs. 10%,
p<0.01). Cardiac arrest or syncope as presenting symptoms was more often
observed in DCM patients (p=0.05). Indications for implantation were equally
distributed among the two groups: Sustained monomorphic ventricular tachycardia
(SMVT) (65% vs. 46%), cardiac arrest (18% vs. 24%), syncope an inducible arrhythmias
(17% vs. 30%). Inducibility of ventricular arrhythmias in the EPS study was
more frequent in MI (99% vs. 76%, p<0.0001), but there was no difference
in the number of extrastimuli needed to induce the arrhythmia or in the SMVT
tolerability. Rapid pacing terminated the tachycardia more often in MI patients
(54% vs. 36% p=0.04). Follow-up period was 21±12 vs. 25±23 months
for MI and DCM respectively (p=NS). Mortality was 6% in both groups. There were
no differences between the two groups in terms of arrhythmia recurrence (52%
vs. 58%), number of episodes/patient (1.3±2.8 vs. 2.8±5.5) and
the rate of VT episodes (188±29 vs.198±31 bpm). Effectiveness
of antitachycardia pacing in DCM was 86%.

Conclusions: Despite baseline
differences between DCM and MI in terms of ejection fraction functional class
and EPS the probability and the number of arrhythmia recurrences are similar
in both populations. ATP was also highly
effective in DCM patients.

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